Example: Configuring sFlow Technology to Monitor Network Traffic on EX Series Switches
You can configure sFlow technology, designed for monitoring high-speed switched or routed networks, to continuously monitor traffic at wire speed on all interfaces simultaneously. sFlow data can be used to provide network traffic visibility information.
This example describes how to configure and use sFlow monitoring. Junos OS fully supports the sFlow standard described in RFC 3176, InMon Corporation's sFlow: A Method for Monitoring Traffic in Switched and Routed Networks (see http://faqs.org/rfcs/rfc3176.html).
Requirements
This example uses the following hardware and software components:
- Junos OS Release 9.3 or later for EX Series switches
- One EX Series switch
Overview and Topology
sFlow technology is a statistical-sampling–based network monitoring technology for high-speed switched or routed networks. sFlow technology samples network packets and sends the samples to a monitoring station. The information gathered is used to create a network traffic visibility picture.
An sFlow monitoring system consists of an sFlow agent embedded in the switch and a centralized collector. The sFlow agent runs on the switch. It combines interface counters and flow samples and sends them across the network to the sFlow collector. Figure 1 depicts the basic elements of the sFlow system.
Figure 1: sFlow Technology Monitoring System
Configuration
To configure sFlow technology, perform the following tasks:
CLI Quick Configuration
To quickly configure sFlow technology, copy the following commands and paste them into the switch terminal window:
[edit protocols sflow]
set collector 10.204.32.46
Set collector udp-port 5600
set interfaces ge-0/0/0
set polling-interval 20
set sample-rate 1000
Step-by-Step Procedure
To configure sFlow technology:
- Configure the IP address of the collector:
[edit protocols sflow]
user@switch# set collector 10.204.32.46
Note: You can configure a maximum of 4 collectors.
- Configure the UDP port of the collector. The default
UDP port assigned is 6343.
[edit protocols sflow]
user@switch# set collector udp-port 5600 - Enable sFlow technology on a specific interface:
[edit protocols sflow]
user@switch# set interfaces ge-0/0/0Note: You cannot enable sFlow technology on a Layer 3 VLAN-tagged interface.
You cannot enable sFlow technology on a link aggregation group (LAG) interface--that is, an aggregated Ethernet interface with a name such as ae0. You can enable sFlow technology on the member interfaces that make up the LAG.
- Specify how often the sFlow agent polls the interface:
[edit protocols sflow]
user@switch# set polling-interval 20Note: The polling interval can be specified as a global parameter also. Specify 0 if you do not want to poll the interface.
- Specify the rate at which packets must be sampled:
[edit protocols sflow]
user@switch# set sample-rate 1000
Results
Check the results of the configuration:
user@switch# show
polling-interval 20;
udp-port 5600;
sample-rate 1000;
collector 10.204.32.46;
interfaces ge-0/0/0.0;
Verification
To confirm that the configuration is correct, perform these tasks:
- Verifying That sFlow Technology Has Been Configured Properly
- Verifying That sFlow Technology Is Enabled on the Intended Interface
- Verifying the sFlow Collector Configuration
Verifying That sFlow Technology Has Been Configured Properly
Purpose
Verify that sFlow technology has been configured properly.
Action
Use the show sflow command:
user@switch> show sflow sFlow : Enabled Sample limit : 300 packets/second Polling interval : 20 seconds Sample rate : 1:1000 Agent ID : 10.204.96.222
| Note: The sample limit cannot be configured and is set to 300 packets/second. |
Meaning
The output shows that sFlow technology is enabled and specifies the values for the sample rate, sample limit, and polling interval.
Verifying That sFlow Technology Is Enabled on the Intended Interface
Purpose
Verify that sFlow technology is enabled on interfaces and display the sampling parameters.
Action
Use the show sflow interface command:
user@switch> show sflow interface
Interface Status Sample rate Adapted sample rate Polling-interval ge-0/0/0.0 Enabled 1000 16000 20
| Note: The sample limit cannot be configured and is set to 300 packets/second. |
Meaning
The output indicates that sFlow technology is enabled on the ge-0/0/0.0 interface with a sampling rate of 1000, sampling limit of 300 packets per second and a polling interval of 20 seconds.
Verifying the sFlow Collector Configuration
Purpose
Verify the sFlow collector's configuration.
Action
Use the show sflow collector command:
user@switch> show sflow collector
Collector address UDP-port No of samples 10.204.32.46 5600 1000 10.204.32.76 3400 1000
Meaning
The output displays the IP address of the collectors and the UDP ports. It also displays the number of samples.
